Patients with ocular toxoplasmosis, pars planitis, sarcoidosis, Behcet's disease, chorioretinitis of unknown origin, and birdshot retinochoroidopathy are being studied to determine the phenotype frequency of the HLA, ABO, and B-cell alloantigens. Becuase the B-cell alloantigens or DF antigens are thought to play a role in the immunologic response to antigens, these findings will complement other immune uveitis studies being simultaneously carried out.